Device for Conveying Tablets

ABSTRACT

A device for conveying tablets has a lower part, an upper part with at least one guide channel for holding and conveying the tablets, and several elastic elements, arranged a certain distance apart, on each of which at least one piezoelectric vibratory element is mounted, wherein the elastic elements are arranged between the upper part and the lower part and connect the two parts together. In addition, the device has at least one control unit for exciting the piezoelectric vibratory elements and thus the elastic elements and a sorting device installed in the area of the guide channel to separate the good tablets from the bad.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority based on European patent application EP 07 011 833.6, filed Jun. 15, 2007.

FIELD OF THE INVENTION

The invention pertains to systems for conveying tablets.

DESCRIPTION OF THE PRIOR ART

Devices for conveying tablets are used in the drug packaging industry as part of a filling device, for example, by means of which bottle-like containers can be filled with a large number of tablets, so that a patient will have a sufficient quantity of tablets available for several weeks of daily administration, for example. So that the containers can be filled with the correct number of tablets, it is necessary to single out the tablets before the bottles are filled so that a product inspection and a counting operation can be performed.

There are several different possibilities for doing this. The tablets are usually brought up by a conventional vibratory conveyor, introduced into a filling tube, and detected and counted as they drop into the container. Conveying tablets by means of a conventional vibratory conveyor sometimes damages the tablets. In addition, product control is more or less impossible in this way, and the reaction of the system upon reaching the desired number of tablets is slightly delayed, so that sometimes a wrong number of tablets arrives in a container.

In other types of filling devices as well, the tablets are usually brought up by a conventional vibratory conveyor, singled out by means of a complicated mechanism, and detected individually before they are deposited in the containers; see, for example, EP 1 389 583 A1 or U.S. Pat. No. 6,505,460 B2. These types of filling devices are complicated to manufacture, but in addition they have not yet been developed to the point where they are ready for the market. Product inspection or counting is known from DE 102 42 243 A1. The tablets are sent along guide channels of a vibratory conveyor, which comprises an opening in the bottom of the guide channel for the automatic discharge of mechanically damaged tablets.

Piezoelectric vibratory conveyors are also known, which are used in various areas outside the pharmaceutical industry; see, for example, DE 100 05 933 B4, DE 203 20 326 U1, and DE 103 40 455 B4. Using these types of conveyors for tablets has been considered too expensive so far, because electromagnetic vibratory conveyors can be manufactured much more cheaply, and also because piezoelectric vibratory conveyors were not originally designed to single out tablets.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a conveying system for tablets in which the tablets can be conveyed, counted, and inspected easily and reliably.

According to an aspect of the invention, the conveying system for tablets includes two devices for conveying the tablets, each having a lower part, an upper part with at least one guide channel for holding and conveying the tablets, and several elastic elements, arranged a certain distance apart from each other, to each of which at least one piezoelectric vibratory element is attached, wherein the elastic elements are arranged between the upper part and the lower part and connect them together. The conveying system also includes at least one control unit for exciting the piezoelectric vibratory elements and thus the elastic elements, and a sorting device, located in the area of the guide channels, for separating the good tablets from the bad tablets.

The two devices are arranged in a cascade, so that the guide channel of the device coming first in the direction in which the tablets are conveyed is higher than the guide channel of the second device. In addition, the conveying system has an inspection device above each of the guide channels of the second device to check the quality of the tablets being conveyed down the guide channel. The second device conveys the tablets at a higher speed than the first device, and the speed at which the tablets are conveyed can be controlled to single them out from each other so that they can be subjected to the quality control operation performed by the inspection device.

As a result of this arrangement, it is ensured that the tablets are singled out in the guide channel. This is necessary so that the tablets can be counted easily and so that the quality inspection of the individual tablets can be carried out while they are still in the guide channel. In addition, because both the inspection device and the sorting device are located in the area of the guide channel, it is easy to separate the good tablets from the bad.

Each upper part preferably comprises a plurality of guide channels, arranged parallel to each other, as a result of which manufacturing costs can be decreased and the overall throughput of the device increased.

So that the good tablets can be separated easily from the bad, it is advantageous for each guide channel to comprise a tablet pass-through opening, which is located close to one of the longitudinal walls of the guide channel.

So that the good tablets can be separated even more efficiently from the bad, each guide channel comprises an angled section or depression extending longitudinally toward the pass-through opening, the width of this angled section or depression being smaller than the width of the guide channel. Thus it is possible for certain tablets to be moved down the angled section or depression toward the pass-through opening at the same time that the other tablets are being conveyed along the web, which occupies the rest of the width of the guide channel.

The inspection device for checking the quality of the tablets being conveyed down the guide channel is designed as an NIR measuring device, as a capacitive probe, as a laser, or as a camera.

A simple mechanical arrangement of the device consists in mounting the elastic elements by means of clamping blocks, each of which is attached to the upper part or to the lower part.

An especially effective vibratory conveying device is obtained by designing each of the elastic elements as a support plate, which is arranged transversely to the conveying direction of the tablets and which is connected to the clamping blocks by screws, wherein two piezoceramic plates, serving as piezoelectric vibratory elements, are mounted on each support plate a certain distance apart.

So that the tablets can be singled out even more effectively, each guide channel can comprise sections arranged in the form of a cascade proceeding in the direction of tablet conveyance.

The tablets can be conveyed at an especially high speed while simultaneously avoiding the accumulation of several tablets in one guide channel by setting each guide channel at an angle of 0-10°, and preferably of 5-7°, to the horizontal and by setting the elastic elements at an angle of 83-89°, preferably of 86-87°, to the lower part.

The sorting device can be advantageously designed as an electromagnetically actuatable finger, which can be moved transversely to the transport direction of the tablets, or as a device for delivering a blast of air. Both mechanisms can be activated and deactivated as a function of the result of the quality control operation.

As previously mentioned, the two devices are arranged to form a cascade, so that the guide channel of the device coming first in the direction of tablet conveyance is higher than the guide channel of the second device, wherein the second device conveys the tablets at a higher speed than the first device. This is accomplished, for example, by setting the second device at a greater angle to the horizontal than the first device. Alternatively or in addition, the elastic elements of the second device can be excited at a higher frequency than the elastic elements of the first device. Thus the tablet streams at the transition between the guide channels are pulled apart very effectively, and the tablets are singled out.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional details, features, and advantages of the present invention can be derived from the following description, which is based on the drawings.

FIG. 1 is a perspective view of a device for conveying tablets, which forms a part of the inventive conveying system;

FIG. 2 is a perspective view of the supporting parts of the device for conveying tablets, wherein the upper part with the guide channels is not shown;

FIG. 3 is a schematic diagram of a special embodiment of the elastic element with two piezoceramic plates mounted on it;

FIG. 4 is a perspective view of a variant of the device for conveying tablets;

FIG. 5 is a side view of the device for conveying tablets; and

FIG. 6 is a perspective view of an inventive conveying system for tablets.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an exemplary embodiment of a device for conveying tablets, which forms a part of the inventive conveying system. In the example shown here, the device for conveying tablets comprises an upper part 2 with three parallel guide channels 4 to hold and convey the tablets 6. In addition, the device has a lower part 8, which stands on rubber feet 10. As shown in FIG. 2, upper part 2 and lower part 8 are connected by several elastic elements 12, arranged a certain distance apart from each other.

By means of the vibratory conveying system described further below, it is possible to single out tablets 6 being supplied to a guide channel 4 by using control devices (not shown) to actuate suitably the individual components of the vibratory conveying system, in such a way that each tablet 6 can be counted exactly and subjected individually to quality control.

It is possible to arrange nearly any desired number of guide channels 4 next to each other, wherein a number of two to four guide channels 4 is currently preferred.

Each guide channel 4 has two longitudinal boundary walls 14, which determine the U-shaped design of the guide channels 4 and define the direction in which tablets 6 are conveyed. In a terminal section of guide channels 4, near one of the longitudinal walls 14, an angled section or recess 16, extending in the longitudinal direction, is provided, the width of which is smaller than the width of guide channel 4. In the example shown here, the width of the recess 16 is approximately half the width of guide channel 4. The section 20, which remains on the other side of guide channel 4, can also, like recess 16, slant down toward its associated longitudinal wall 14; that is, a profile is formed with a crest 18 in the middle of guide channel 4. It is also possible that recess 16 could have a different shape, and that section 20 could be designed as a web. There are many possible mechanical designs which could be used here to ensure the effective division of guide channel 4 into two areas. In some cases it would even be possible to leave out recess 16.

In the preferred embodiment shown here, each guide channel 4 also has a pass-through opening 22, located near one of the longitudinal walls 14 of guide channel 4, for tablets 6. The pass-through opening 22 serves here to accept tablets 6 which have been identified as “good” and leads to a filling tube (not shown), which, during operation, remains closed at its bottom end by a cap until the desired number of tablets 6 has been verified by a counting device (also not shown), which counts the tablets remaining on guide channel 4. Then the cap is opened, and the predetermined number of tablets 6 is discharged into the appropriate bottle-like or can-like container. For this purpose, several devices, parallel to each other, are preferably used, so that a larger number of containers can be filled simultaneously. It is also conceivable that the device for conveying tablets could be used in other applications in which tablets are to be fed forward without damaging them.

In addition to the previously mentioned counting device, an inspection device (not shown) is installed above each guide channel 4 to check the quality of tablets 6 being conveyed down guide channel 4. The inspection device can be, for example, a conventional camera, which merely examines the tablets for lamination, capping, picking, etc., but it could also be designed as a NIR measuring device, which can check the consistency of tablets 6. A capacitive probe, a laser, or any other desired type of inspection device could also be used. Downstream of the inspection device, a sorting device 24 is provided, which serves to separate tablets 6 found to be “good” from those found to be “bad”. In the example shown in FIG. 1, the sorting device 24 is designed as an electromagnetically actuated finger, which can move transversely to the direction in which tablets 6 are being conveyed and which, when actuated, pushes a tablet 6 from section 20 of guide channel 4 into recess 16. It is also conceivable that a device for delivering a blast of air transversely to the direction in which tablets 6 are being conveyed could be provided as a sorting device 24. In the example shown, tablets 6 found to be good are moved by sorting device 24 into recess 16, where they continue to travel until they reach the pass-through opening 22. It is equally possible to actuate sorting device 24 only when a tablet 6 found to be bad is to be separated out. Because most of tablets 6 will be classified as good, this reduces the actuating rate of sorting device 24. Tablets 6 classified as bad can then be sent through pass-through opening 22, or no pass-through opening 22 at all can be provided, and instead the good and bad tablets 6, which have been separated from each other, can continue to travel until they reach end of guide channel 4, at which point they are then processed separately.

FIG. 2 shows the vibratory conveyor system of the device in detail. The lower part 8 comprises a base plate 26, from which longitudinally oriented side plates 28 project upward. The side plates 28 extend along each of the longitudinal sides of the base plate 26 and are arranged in a row, a certain distance apart. Clamping blocks 30 are attached to the end surfaces of side plates 28 by screws 32. A support plate is clamped between the clamping block 30 and side plate 28; in the present example, this support plate forms elastic element 12. Two piezoelectric vibratory elements 34 are mounted on support plate 12, which forms a connection between two side plates 28 and is arranged transversely to the conveying direction of tablets 6. It has been found to be especially advantageous to use piezoceramic plates as piezoelectric elements 34, as a result of which a double spring is formed, which ensures the production of up to 30,000 longitudinal linear vibrations per minute.

A piezoelectric vibratory element 34 of this type is shown in detail in FIG. 3. Piezoceramic plates 34 are set into vibration by a suitable alternating voltage applied by a control unit (not shown) by way of a cable 36. These vibrations are transmitted to the support plate, acting as elastic element 12, and excite it. In principle, it can also be sufficient to provide merely one piezoelectric vibratory element 34 on elastic element 12. The connection between elastic element 12 and piezoelectric vibratory element 34 is preferably accomplished by means of an adhesive, but other types of attachment are also conceivable.

By using several coordinated control units, each of which applies an alternating voltage to piezoelectric vibratory elements 34, to actuate the various piezoelectric vibratory elements 34, which are arranged a certain distance apart, in a coordinated manner, it is possible to move the tablets along the downward slanting guide channel 4 in almost any way desired. Thus, in the inventive conveying system, it is also possible to single out tablets 6 from each other in each guide channel 4.

The middle area of support plate 12 is also attached by a clamping block 38 to an angle profile 40, which is connected to upper part 2 of the device. In this way, the vibrations generated by the vibratory conveyor system are transmitted to upper part 2 and thus also to guide channels 4.

The design of piezoelectric vibratory elements 34 and of elastic elements 12 can be modified as desired on the basis of existing developments in the area of piezoelectric conveyor technology. Thus, for example, piezoelectric vibratory element 34 can comprise additional layers or be designed in different ways. The mechanical connection between elastic element 12 and upper part 2 or lower part 8 of the device can also be modified.

FIG. 4 shows a variant of the device, in which the singling-out of tablets 6 in guide channels 4 is supported by dividing guide channel 4 into several successive sections, following each other in the longitudinal direction in the manner of a cascade.

It is has been found by experiment that the angle a to the horizontal shown in FIG. 5, which is the same as the angle between slanted lower part 8 and the floor, should be in the range of 0-10°, and preferably in the range of 5-7°. At an angle in this range, a transport rate of up to 20 m/min is possible in the previously described examples, which corresponds to the transport of approximately 1,000 tablets/min at a distance between products of 5-10 mm in guide channel 4. Tablets 6 essentially slide down guide channels 4. Certain nodal points or dead areas in guide channel 4 can be avoided by the use of leveling compounds.

The spring angle β between elastic elements 12 and lower part 2 should be in the range of 83-89°, and preferably in the range of 86-87°. As a result, a relatively balanced relationship is obtained between vertical and horizontal acceleration of tablets 6.

FIG. 6 shows a conveyor system according to the invention which is especially advantageous with respect to the singling-out of tablets 6 from each other. In this system, one of the previously described devices is combined with a device which is of similar design but which does not comprise a sorting device 24. The two devices are arranged in a cascade in such a way that the guide channel 4′ of the device coming first with respect to the direction in which tablets 6 are conveyed is higher than guide channel 4 of the second device, wherein the second device conveys tablets 6 at a greater speed than the first device does. This is accomplished, for example, in that the second device has a greater angle α to the horizontal than the first device. Alternatively or in addition, elastic elements 12 of the second device can be excited at a higher frequency than the elastic elements 12′ of the first device. Thus the tablet streams are drawn apart especially effectively at the transition between the two guide channels 4′, 4, and tablets 6 are singled out from each other. Sorting device 24, normally provided, is not shown here.

Within the scope of the present invention, all other types of solid medications such as capsules, dragees, etc., are also considered tablets 6. The inspection device checks the tablets for defects such as breakage, color, or active ingredient, and the bad tablets are sorted out while they are still in guide channel 4. Thus a conveying system for tablets is provided, which moves the tablets along at a controllable transport speed in a gentle manner not damaging to the tablets and which at the same time ensures that the tablets are singled out from each other, which makes it possible for the tablets to be counted and to be subjected to quality control while they are still in the guide channel 4. 

1. A conveying system for tablets comprising: two devices for conveying tablets, each having a lower part, an upper part with at least one guide channel for holding and conveying the tablets, and several elastic elements, arranged a certain distance apart from each other, to each of which at least one piezoelectric vibratory element is attached, wherein the elastic elements are arranged between the upper part and the lower part and connect them together, wherein the two devices are arranged in a cascade, so that the guide channel of the device coming first in the direction in which the tablets are conveyed is higher than the guide channel of the second device; at least one control unit for exciting the piezoelectric vibratory elements and thus the elastic elements; an inspection device located above each guide channel of the second device to check the quality of the tablets being conveyed in the guide channel; and a sorting device, located in the area of each guide channel, to separate the good tablets from the bad, wherein the second device conveys the tablets at a higher speed than the first device, and the speed at which the tablets are conveyed can be controlled to single out the tablets from each other for the quality control operation performed by the inspection device.
 2. The conveying system for tablets according to claim 1 wherein the second device has a greater angle to the horizontal than the first device.
 3. The conveying system for tablets according to claim 1 wherein the elastic elements of the second device are excited at a higher frequency than the elastic elements of the first device.
 4. The conveying system for tablets according to claim 1 wherein each upper part comprises a plurality of guide channels arranged parallel to each other.
 5. The conveying system for tablets according to claim 1 wherein each guide channel of the second device has a pass-through opening for tablets, which is arranged near one of the longitudinal walls of the guide channel.
 6. The conveying system for tablets according to claim 1 wherein each guide channel of the second device has an angled section or recess extending in the longitudinal direction leading to the pass-through opening.
 7. The conveying system for tablets according to claim 1 wherein the inspection device for checking the quality of the tablets being conveyed in the guide channel is designed as a NIR measuring device, as a capacitive probe, as a laser, or as a camera.
 8. The conveying system for tablets according to claim 1 wherein the elastic elements are held in place by clamping blocks, each of which is attached to the upper part or to the lower part.
 9. The conveying system for tablets according to claim 1 wherein each elastic element is designed as a support plate, which is mounted transversely to the direction in which the tablets are conveyed and is connected by screws to the clamping blocks, wherein two piezoceramic plates serving as piezoelectric vibratory elements are mounted on each support plate a certain distance apart.
 10. The conveying system for tablets according to claim 1 wherein each guide channel has sections arranged in the form of a cascade extending in the direction in which the tablets are conveyed.
 11. The conveying system for tablets according to claim 1 wherein the angle of each guide channel to the horizontal is in the range of 0-10° , and preferably in the range of 5-7°, and the angle of the elastic elements to the bottom part is in the range of 83-89°, and preferably in the range of 86-87°.
 12. The conveying system for tablets according to claim 1 wherein the sorting device comprises an electromagnetically actuated finger, which can be moved transversely to the direction in which the tablets are conveyed.
 13. The conveying system for tablets according to claim 1 wherein the sorting device comprises a device for delivering a blast of air. 